The carbonated water required for this purpose is chilled and stored under pressure. In a manner known from the prior art, this carbonated water is dispensed via a shutoff valve and, in some cases, via a pressure-reducing valve in series therewith for the mixing process. To a large extent, the quality of the blended beverage is dependent on the mixing ratio of beverage concentrate to carbonated water. Therefore, it is essential that steps be taken to ensure the mixing ratio needed for the different conditions prevailing during normal operation. For example, techniques are known for determining the quantity of beverage concentrates by means of metering chambers.
Particularly as a result of the considerably larger quantity of carbonated water added, the latter is dispensed in the known manner in a continuous flow, with the quantity determination resulting from the quantity dispensed per unit time and from the dispensing time. The dispensing time can easily be controlled by control measures known from the prior art. Problems may arise in the area of the mechanical dispensing unit, because the prior art techniques are not capable of determining sufficiently accurate flow volumes per unit time. A not negligible disturbance variable is seen in the fact that the liquid is supplied to the dispensing unit under different pressure conditions.